UHDI Fundamentals: Talking UHDI with John Johnson, Part 2

Estimated reading time: 2 minutes

Editor’s note: This is the second of a three-part interview. To read Part 1, click here.

American Standard Circuits is an early adopter of Averatek’s A-SAP™ process for its ultra-high density interconnect (UHDI) products. I had the opportunity to sit down with industry veteran John Johnson to discuss this. John previously worked at Averatek and is now vice president of business development at American Standard Circuits where he oversees quality. In the spirit of full disclosure, we will be discussing and sharing photos, slides, and materials with permission from both ASC and Averatek.

Steve Williams: John, American Standard Circuits is a big RF manufacturer. Is there a big application for UHDI in that niche?

John Johnson: Yes, absolutely. From a signal integrity side and getting that straight sidewall, it benefits a lot. But this technology works very well to produce very, very low surface profiles, and that’s an additional benefit. When you look at just building boards with controlled impedance, you can get to a much tighter tolerance. We talk in the industry of typically ±10%, but we can do 5%, so this can get you down to a much tighter tolerance the first time out of the box because you're building right to the design. Your trace will be right there, and since you're plating up a trench—that little trench gets filled up—and that's exactly at the width the designer intended, so it's a lot easier to hit the impedance requirements. Also, this technology has a lot of potential in the medical industry. You can make biocompatible circuit boards because A-SAP does not have any copper or nickel in the construction—which are toxic to the body. You can do traces that are all noble metals like palladium and gold, and that's a big improvement.

Williams: Are you doing anything biocompatible? Johnson: We are. We've built a couple of programs here with more to come. Williams: One of the foundations of the process is liquid metal ink (LMI™). Tell me about that.

Johnson: LMI is a patented Averatek chemistry for putting down a very, very thin coating of palladium on the surface. It’s very dense—basically several levels deep of atoms touching atoms. It’s just a few nanometers thick. That density really helps in getting plating down into all the small crevices and small vias that need to be plated. The liquid metal ink is a non-aqueous base, so that wets very well in all the little nooks and crannies that you'll see in drilled holes. You can metallize these holes much easier than standard plating chemistry...

Continue reading this interview in the December 2023 issue of Design007 Magazine.